And now anyone can enjoy the fun with Threes! Free. Instead of pop-up ads or some kind of other annoying system that is common with free games, developer Sirvo has designed a unique gameplay system for the game.

You’ll earn virtual credits by watching ads, and then you spend them to play the game. If the ads are annoying, you can upgrade to the paid version.

Here’s how the free version of the game will work.

Designer Asher Vollmer told Polygon that the free version has been in the works for more than a year as the team decided how to create something different for gamers.

“A year ago I thought that cheapening the game experience for the free version was okay,” Vollmer said.

“My stance was a little vitriolic… it was along the lines of ‘oh if you actually want a good experience then you should pay for it!’ But I’ve started actually talking to people who play free games and I respect the fact that they have a sensitive relationship to money. I still want to give them a chance to play the game and I still want them to have a good experience and I still want to be supported as a developer.”

If you haven’t heard of the game, it’s a fun and exciting take on the usual puzzler. You’ll need to match numbers to build larger tiles. While it seems simple, the game is extremely difficult to actually master.

I’m always a fan of puzzle games — it’s one of my favorite types of things to play on my iPhone, and I always lose several hours of my day to it at once. Threes is definitely no exception, but I believe that it is one of the most addictive little puzzle games that has embraced my device for quite some time now. In fact, I had a hard time putting my phone down yesterday because of this game, all the way up to the wee hours of the morning. If you appreciate a good puzzle game, then Threes is one you’re going to have to add to your collection, even if you’re not a big numbers person.